Marquette University law professor Ed Fallone will face Wisconsin Supreme Court Justice Pat Roggensack in the April election.
Fallone finished second in Tuesday's Supreme Court primary, behind Roggensack but well ahead of challenger Vince Megna. In unofficial returns, Roggensack took 60 percent of the vote to Fallone's 33 percent. Megna was far back in single digits.
Fallone argues that the Supreme Court is dysfunctional and Roggensack is partially to blame.
Roggensack said voters should decide on her merits, not the court's. She also said justices get along better than people think.
Democratic lawmakers and unions are supporting Fallone in the nonpartisan race. Roggensack has the backing of more than 150 county sheriffs and judges.
The winner of the April 2 general election gets a 10-year term on the bench.